The Arsenal defender says the die Mannschaft must improve defensively if they are to have any chance at winning the World Cup in Brazil next summer
Joachim Low's side have shipped nine goals in their last three internationals and let a 4-0 lead slip at home to Sweden last October, with the game ending 4-4.
"The players and coaches have come together to discuss the basic principles of our defence," he told dfb.de.
"We've been playing a different system so we need to learn the philosophy for this shape. We need to know when to drop back, when to move out, how to deal with certain situations and how to protect one another."
Germany take on Austria at the Allianz Arena in Group C on Friday night and Mertesacker is hoping for a collective team effort in become a more resolute defensive unit.
"Goals often come from a mistake much further up the field, yet the analysis and blame will always be on the defence," he added.
"We cannot take responsibility for every goal we concede, we all need to do our part across the field to ensure we win as a team."
Die Mannschaft currently lead Austria by five points at the top of their group with five wins from their six qualifiers to date.